The operation of heavy mechanical equipment such as large tractors generates considerable heat in the engines of the equipment, which must be efficiently dissipated to prevent damage to the engine. This is generally accomplished by coolant-based radiator systems, in which a pump circulates coolant through tubes in a radiator. Air cools the tubes and, hence, the coolant, and the coolant is then pumped through various engine components, e.g., an engine oil cooler, to cool these components.
As recognized herein, many engines of heavy equipment are turbocharged. Turbochargers generate charge air for the engine which is used in the combustion process. To reduce engine emissions, the temperature of the charge air from the turbocharger should be minimized, and aftercoolers have been provided for this purpose. Coolant from the radiator can be used to cool the turbocharged air passing through an aftercooler.
Thus, it is important to minimize coolant temperature at normal operating conditions, both to effectively cool engine components and to reduce emissions in turbocharged engines. As recognized herein, however, it is further important to provide appropriate coolant flow rates at light loads, i.e., when the engine generates relatively little heat. The present invention under-stands that both of these problems can be addressed in a manner that is superior to that provided by existing cooling systems.